The Mu factor ..
A measure of the relative effect of the voltages on two electrodes upon the current in the circuit of any specified electrode. It is the ratio of the change in one electrode voltage to a change in the other electrode voltage, under the condition that a specified current remains unchanged.
Now that sure clears that up. Get the 6K5GT.
http://www.nj7p.org/Tube4.php?tube=6k5gt
Then look at the 6K5G ..
The GT has a smaller, cylindrical-shaped envelope. I suppose there is a rare chance that a G would occupy too much room if the set were laid out for a GT.
The G shape is older looking, and might appeal to some on appearance grounds.
Doug
May as well add this too.
Warren J. Dougherty, a serviceman of Kinkaid, Kansas, has called to our attention one of the factors most overlooked when replacing G-type tubes with the more newly-designed GT tubes. Invariably these GT tubes, with metal base, have their No. 1 pin grounded. Inasmuch as many manufacturers use all available socket pins for common tie-points, considerable damage may be caused when grounding the No. 1 pin. A particular case is the RCA Model BT-42 which was originally equipped with G-type tubes. When changing to GT tubes with metal base, the condenser, C16, 400-µfd. condenser and 1-megohm resister, R7, in the plate circuit of the 1H5 should be disconnected from the No. 1 pin of the 1N5 tube socket, as in this particular case, it was used as a common terminal connector. The metal base occasionally will short out the plate voltage from the 1H5 tube, resulting in a nonoperating receiver.
::A GT or a G refers to the shape of the glass envelope. No other difference.
::
::The GT has a smaller, cylindrical-shaped envelope. I suppose there is a rare chance that a G would occupy too much room if the set were laid out for a GT.
::
::The G shape is older looking, and might appeal to some on appearance grounds.
::Doug
:
:May as well add this too.
:
: Warren J. Dougherty, a serviceman of Kinkaid, Kansas, has called to our attention one of the factors most overlooked when replacing G-type tubes with the more newly-designed GT tubes. Invariably these GT tubes, with metal base, have their No. 1 pin grounded. Inasmuch as many manufacturers use all available socket pins for common tie-points, considerable damage may be caused when grounding the No. 1 pin. A particular case is the RCA Model BT-42 which was originally equipped with G-type tubes. When changing to GT tubes with metal base, the condenser, C16, 400-µfd. condenser and 1-megohm resister, R7, in the plate circuit of the 1H5 should be disconnected from the No. 1 pin of the 1N5 tube socket, as in this particular case, it was used as a common terminal connector. The metal base occasionally will short out the plate voltage from the 1H5 tube, resulting in a nonoperating receiver.
The other Warren not me is correct. But he is talking about the GT types such as the 1N5 found in the old filament type farm radios. I have an RCA 55F that has all GT tubes, such as 1A7 1H5 and even the output 3Q5. All have a metal base. Have A peek here.
http://www.nj7p.org/Tube4.php?tube=1N5GT
:
:
:::A GT or a G refers to the shape of the glass envelope. No other difference.
:::
:::The GT has a smaller, cylindrical-shaped envelope. I suppose there is a rare chance that a G would occupy too much room if the set were laid out for a GT.
:::
:::The G shape is older looking, and might appeal to some on appearance grounds.
:::Doug
::
::May as well add this too.
::
:: Warren J. Dougherty, a serviceman of Kinkaid, Kansas, has called to our attention one of the factors most overlooked when replacing G-type tubes with the more newly-designed GT tubes. Invariably these GT tubes, with metal base, have their No. 1 pin grounded. Inasmuch as many manufacturers use all available socket pins for common tie-points, considerable damage may be caused when grounding the No. 1 pin. A particular case is the RCA Model BT-42 which was originally equipped with G-type tubes. When changing to GT tubes with metal base, the condenser, C16, 400-µfd. condenser and 1-megohm resister, R7, in the plate circuit of the 1H5 should be disconnected from the No. 1 pin of the 1N5 tube socket, as in this particular case, it was used as a common terminal connector. The metal base occasionally will short out the plate voltage from the 1H5 tube, resulting in a nonoperating receiver.
Hi-mu has to do with amplification factor (to a degree, I believe). A hi-mu tube will have more gain than a medium or low-mu tube.
6SQ7 is a hi-mu tube. 6SR7 is a low-mu tube. If you put a 6SR7 in a 6SQ7 socket, the audio won't be as loud (most likely, though not definitely).
T.
:Hi folks,
:I thought a 6K5 was a 6K5 electrically no matter what the following letters are which I thought designated the style of the tube. I see I can get a 6K5G from AES for $16.74 and a 6K5GT for $4.32. Only difference at AES is one is listed as a "Triode" and the later as a "Triode, HI MU" which I don't know what "HI MU" means. Can someone clarify this for me and what does "HI MU" stand for? Thanks, Johnny
The only other issue no one mentioned is that of 1938 Philco sets. They used a metal base for the square shields that don't allow a 6K5GT to fit in. I had a Philco 38-5 years ago that needed a 6K5G. I used a 6K5GT and had to cut the shield base out a little larger to allow the larger diameter base of the GT version to fit in. The 1937 Philco sets, some of which also used 6K5G in them don't have the problem and either will physically fit with no mods.
FR
:Take a look at findatube.com, they have new and used, both GT & G. A new GT is 7.00 and a used is 3.00. I have purchased quite a few from him, service is quick and never had a problem with either a new or used tube.
:Shipping is normally 5.00 for priority mail for a small quanity of tubes.
:Bob Z
:
:Bob, I think buying used tubes that are tested is a good idea. I have done it a lot for pre-octals.
:Doug
:
::Take a look at findatube.com, they have new and used, both GT & G. A new GT is 7.00 and a used is 3.00. I have purchased quite a few from him, service is quick and never had a problem with either a new or used tube.
::Shipping is normally 5.00 for priority mail for a small quanity of tubes.
::Bob Z
::
: